The present invention relates to a buffer of an elastic material, preferably rubber, which can be clamped into an annular slot formed between the shoulder of a wheel-disk and a wheel-rim of a rail-wheel for electrical vehicles. The opposite sides of the buffer which abut the wheel center-disk and the wheel-rim of said buffer, are connected with each other in recesses of the buffer element by means of contact elements for the purpose of providing an electrical connection from the wheel center-disk with the wheel-rim by means of a flexible conduit; each of the contact elements includes a contact-plate and a rivet head connected therewith, whereby the rivet head represents the ends of the conduit which are riveted together.